Re-evaluating rhythmic attentional switching: Spurious oscillations from shuffling-in-time

How does attention help to focus perceptual processing on the important parts of a visual scene? Although the neural and perceptual effects of attention were traditionally assumed to be sustained over time, the field is converging on a dramatically different view: that covert attention rhythmically switches between objects at 3-8 Hz. Here I demonstrate that ubiquitous analyses in this literature conflate rhythmic oscillations with aperiodic temporal structure. Using computational simulations, I show that the behavioral oscillations reported in this literature could reflect aperiodic dynamics in attention, rather than periodic rhythms. I then propose two analyses (one novel and one widely used in climate science) that discriminate between periodic and aperiodic structure in behavioral time-series. Finally, I apply these alternative analyses to published data-sets, and find no evidence for rhythms in attentional switching after accounting for aperiodic temporal structure. Attention shows rich temporal structure. The techniques presented here will help to clarify the periodic and aperiodic dynamics of perception and cognition.